β-Deprotonation by lithium di-isopropylamide. Vinyl carbanions from oxygen heterocycles in the synthesis of carboxylic acids in the benzofuran, flavone, and coumarin series and in the regiospecific acylation of 2,6-dimethylchromone
- 1 January 1980
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Chemical Communications
- No. 24,p. 1224-1226
- https://doi.org/10.1039/c39800001224
Abstract
Lithium di-isopropylamide at –70 °C can remove the α-proton from benzofuran in the absence of activating groups and the β-proton if such groups are present; in flavone and 4-methoxycoumarin β-deprotonation occurs readily and the carbanions are easily carboxylated giving acids not previously accessible, while in 2,6-dimethylchromone β-deprotonation is kinetically favoured allowing 3-acylation to be achieved separately from the conventional acylation at the 2-methyl group.Keywords
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